Seroreactive epitopes on proteins of human papillomavirus (HPV) 18

ABSTRACT

The invention relates to seroreactive epitopes on proteins of human papillomavirus HPV18. 
     In addition, the invention relates to peptides which have amino-acid sequences which coincide in whole or in part with the sequences of the seroreactive epitopes, and to vaccines which contain such peptides.

This application is a continuation of application Ser. No. 07/947,992, filed Sep. 21, 1992, now abandoned, which was a continuation of application Ser. No. 07/696,953 filed May 8, 1991, abandoned.

The invention relates to seroreactive regions on proteins E1, E6 and E7 of human papillomavirus (HPV) 18.

The invention also relates to vaccines which contain peptides which embrace amino-acid sequences of the seroreactive regions of the said virus proteins and to diagnostic kits which contain the said peptides.

HPV18 is a specific type of human papillomavirus which was described for the first time in Proc. Natl. Acad. Sci., USA 80, 3813-3815 (1983).

The DNA sequence and the organization of the viral genome of HPV18 were published in Virology 145, 181-185 (1985).

HPV18 induces not only benign lesions of the anogenital tract but also malignant tumors of the neck of the uterus, of the penis and of the vagina. However, HPV18 is also found in genital scrapings from clinically symptom-free individuals. To date little is known about the immune response to infection by HPV18 and other papillomaviruses.

In initial experiments, human sera from STD patients, from patients suffering from cervical tumors and from healthy individuals were tested for the presence of antibodies directed against viral proteins. These viral proteins were expressed as fusion proteins covalently bonded to various procaryotic peptides via their N terminus. Fusion proteins of this type were then used as antigens in Western blot experiments. However, this test is relatively time-consuming and complicated and can be carried out only with great expense, so that it appears unsuitable for quantitative analysis of large quantities of human serum. In addition, this test is not very specific because the various papillomavirus types are also related in respect of their protein core, and thus a cross-reaction of antibodies with proteins or fusion proteins from different papillomavirus types cannot be ruled out.

The object of the present invention is therefore to identify viral structures of HPV18 which are suitable as aids in the prophylaxis, the diagnosis and the therapy of HPV18-induced diseases in humans. Knowledge about such structures (protein domains) is a prerequisite for the establishment of a test with which large quantities of human blood serum can be examined for the presence of specific HPVs.

Thus the present invention embraces a seroreactive epitope on the El protein of HPV18 with the following amino-acid sequence

TENSPLGERLEVDTELSPRLQEISLNS  (SEQ ID No:1)

and seroreactive epitopes on the E6 protein of HPV18 with one of the following amino-acid sequences

I. DPTRRPYKLPDLCTELNTSLQDIEITCVYCKT (SEQ ID No:2)

II. MARFEDPTRRPYKL (SEQ ID No:3)

III. AACHKCIDFYSRIRELRHYSDSVYGDTLEKLT (SEQ ID No:4) and seroreactive epitopes on the E7 protein of HPV18 with one of the following amino-acid sequences

I. VLHLEPQNEIPVDLLCHEQLSDSEEENDEIDGVNHQHLPARRAEPQRH (SEQ ID No:5) and

II. IDGVNHQHLPARR (SEQ ID No:6).

The invention also embraces peptides which contain either one or more than one amino-acid sequence(s) according to the invention of the abovementioned seroreactive epitopes.

The invention also embraces vaccines which are based on peptides which contain one or more amino-acid sequence(s) of the abovementioned seroreactive epitopes of the proteins of HPV18.

Specific antibodies against HPV18 E1, E6 and E7 proteins can be detected in patients' sera using a diagnostic kit according to the invention. This kit contains the peptides according to the invention.

Moreover, it is also possible, with a view to prophylaxis, for the specific viral proteins which contain the seroreactive regions to be identified in blood serum in good time using polyclonal antibodies or monoclonal antibodies which are directed against these regions. Accordingly, this invention also embraces a diagnostic kit which contains polyclonal or monoclonal antibodies which are specifically directed against the seroreactive regions of HPV18.

The following mutually independent methods were used to identify the seroreactive epitopes:

A. Screening of a shotgun expression bank: the HPV18 DNA cloned in the bacterial plasmid vector pSP65 was converted into fragments with an average size of 100 base-pairs by ultrasonic shearing and subsequent DNase treatment. The ends of these fragments were filled in with T4 DNA polymerase and ligated into the phage expression vector fuse 1. Fuse 1 is derived from the bacteriophage fd and is described in Science 228, 1315-1317 (1985). The phages were plated out with Escherichia coli K91, replicas were made on nitrocellulose filters, and the filters were incubated with suitable polyclonal rabbit sera. Positive clones were isolated in several singling-out steps, and the immunoreactive peptide sequences were identified by DNA sequencing.

B. Peptide overlapping

127 overlapping peptides which correspond to short segments of the HPV18 E6 and E7 proteins were synthesized on polyethylene pins using Fmoc chemistry (Proc. Natl. Acad. Sci., 82, 178 (1985)). The protein sequence of the E6 and E7 proteins was divided into 10mers which coincide in 8 amino acids with the next peptide. The peptides were assayed by ELISA in the appropriate antisera.

EXAMPLE 1

Derivatives of the filamentous phage fd were used to obtain an expression system for HPV18 DNA fragments. For this, fuse 1 (fd-tet-J6, Science 228, 1315-1317 (1985); Gene 73, 305-318 (1988)) was cut at the single PvuII cleavage site. Genomic HPV18 DNA fragments from a DNaseI digestion after DNA repair underwent blunt-end ligation with a T4 DNA ligase. To transform the fuse 1 vector, the E. coli strain K802 (F⁻ga1K2 ga1T22 metB1 supE44 hsdr(2); Journal of Molecular Biology 16,118-133 (1966)) was used in the method of Hanahan in Journal of Molecular Biology 166, 557-580 (1988). The tet-resistant colonies produce bacteriophages which are not infectious for the bacteria because of their F⁻phenotype. In order to plate out the phages, the E. coli strain K91 (F⁺, a derivative of E. coli K38, Virology 49, 45-60 (1972)) was used.

EXAMPLE 2

Approximately 50 000 recombinant phages from the random bank described above were plated out with 0.2 ml of exponentially growing E. coli K91 cells in 3.5 ml of 0.5% agarose, which contained 10 mM MgSO₄, on minimal agar plates. Replicas of the plates were made on nitro-cellulose filters and then incubated further at 37° C. on fresh minimal agar for 6 h in order to enhance the signal. The filters were then blocked with 10% low-fat milk in PBS for 60 min and incubated in 5% milk/PBS with a dilution of HPV-specific antisera of from 1:100 to 1:1000 overnight. It is also possible to use monoclonal antibodies in place of the specific HPV antisera. The antisera were preadsorbed with sonicated K91 cells. The filters were then washed 5×, specifically in PBS/0.1% Tween 20 for 5 min and then at room temperature for 3 h with goat anti-rabbit antibodies or, in the case where monoclonal antibodies were used, incubated with anti-mouse peroxidase antibodies (1:1000) in 5% low-fat milk. After the filters had been washed they were stained in 50 ml of PBS which contained 30 mg of diaminobenzidine, 30 μl of 30% strength H₂O₂ and 1.5 ml of 1% strength NiSO₄. The filters were then washed in H₂O for 30 min and then dried on filter paper.

Initially 25 phages were isolated using the polyclonal rabbit serum against HPV18 E7, and 18 of these proved positive in the subsequent purification steps. Subsequently, phage particles were grown in culture and single-stranded DNA was prepared.

EXAMPLE 3

The same approach as in Example 2 was also chosen for HPV18 E6 protein. Since the polyclonal rabbit serum used cross-reacted with non-viral epitopes, besides the Western blot method, specific DNA fragments were used as probes in order to identify among all the reactive recombinants those with HPV18 E6 portions. From 70 000 recombinant phages, 15 were isolated and finally sequenced. The epitope HPV18 E6 No. 1 was thus found a total of 10 times in the investigated phage bank, for example.

EXAMPLE 4

Preparation of Single-stranded DNA from Fuse 1 Recombinants

Used for this was a procedure from Proc. Natl. Acad. Sci., USA 74, 5463-5467 (1977). 50 ml of LM were incubated with tet-resistant E. coli K91 cells which harbored the fuse 1 plasmid, and this mixture was incubated at 37° C. for 16 h. The bacteria were then pelleted at 6000 rpm for 30 min. After addition of 2 ml of 40% strength PEG 6000 and 2 ml of 5 M sodium acetate, pH 6.5, to the supernatant, the phages were precipitated at 0° C. for 60 min, and the precipitate was centrifuged at 6000 rpm for 60 min. The pellet was resuspended in 0.3 ml of TE. Two phenol extractions were followed by precipitation of the DNA. Approximately 25% of the preparations were then used for the sequencing.

EXAMPLE 5

Sequencing

The standard USB (United States Biochemicals) method (USB, 1987) was used for the DNA sequencing. The universal primer was replaced by a 20mer oligonucleotide (5′-TCCAGACGTTAGTAAATGAA-3′(SEQ ID No:7)).

EXAMPLE 6

Peptide Synthesis

127 overlapping peptides which represent in short segments the ORFs HPV18 E6 and E7 were synthesized by Fmoc chemistry on polyethylene pins as described in Proc. Natl. Acad. Sci. 82, 178 (1985) and Proc. Natl. Acad. Sci. 81, 3998 (1985). The polyethylene pins, which were derivatized with β-alanine, were obtained from CRB England. Deviating from the publications cited above, the protein sequence was divided into decapeptides which overlap by 8 amino acids with the adjacent peptide. The synthesis was carried out using Fmoc chemistry and in situ activation by Benzoltriazolyl N-Oxytrisdimethylamino Phosphonium, hereinafter BOP (Castro's reagent) (Tetrahedron Letters, 14, 1219 (1975)). Fmoc-amino acid derivatives (6 μmol), BOP and N-methylmorpholine solution were distributed in polyethylene pins (CRB) corresponding to the peptide sequence which is to be synthesized. All the other reactions were carried out in accordance with the CRB protocol.

EXAMPLE 7

The polyethylene pins were incubated by the ELISA assay method with the above mentioned polyclonal rabbit sera, and bound antibodies were detected using protein A-peroxidase. A background produced by non-specific binding was quantified by protein A incubation without the first antibody. The reactive peptides are located in regions which were identified by the phage screening as seroreactive epitope.

All the assays were carried out on the peptides which were bonded covalently to the polyethylene pins and on which they had originally been synthesized to. Racks with 96 pins which were fixed in such a configuration that they could be introduced into the wells of microtiter plates were used. The incubation for the ELISA was carried out while the pins were immersed in the wells. The pins were washed with methanol and PBS and then blocked with 0.25% gelatin, 0.1% Tween 20 in PBS at 37° C. for 2 h, followed by incubation at 37° C. for 1 h with sera which were diluted 1:200 to 1:4000 in 0.125% gelatin and 0.05% Tween 20. After another washing step with PBS/0.1% Tween 20, the pins were incubated with protein A-peroxidase 1:4000 at 37° C. for 1 h, followed by another washing step and staining with tetramethylbenzidine (TMB) for 15 min. The staining step was stopped by withdrawing the pins from the staining solution and adding 100 μl of a 0.2 molar H₂SO₄ solution. The absorption was then measured in an automatic ELISA reader. In order to remove the antibody-enzyme complex after the ELISA process, the pins were incubated with ultrasound (water bath, 30 W, 48 KHz) at 60° C. in PBS/1% SDS/0.1% β-mercaptoethanol for 1 h and were finally washed with methanol. The efficiency of this procedure was tested by means of an ELISA using protein A/peroxidase without involving a primary serum. The same peptides were assayed more than 40 times in the following ELISAs.

TABLE E1 seroreactive epitope (HPV18) bp1193-TENSPLGERLEVDTELSPRLQEISLNS(SEQ ID NO:1)-bp1273 E6 seroreactive epitopes (HPV18) pb120-DPTRRPYKLPDLCTELNTSLQDIEITCVYCKT(SEQ ID NO:2)-bp215       MARFEDPTRRPYKL(SEQ ID NO:3) bp294-AACHKCIDFYSRIRELRHYSDSVYGDTLEKLT(SEQ ID NO:4)-bp386 E7 seroreactive epitope (HPV18) bp623-VLHLEPQNEIPVDLLCHEQLSDSEEENDEIDGVNHLPARRAEPQRH(SEQ ID NO:5)-bp763       IDGVNHQHLPARR(SEQ ID NO:6)

7 27 amino acids amino acid single linear peptide not provided 1 Thr Glu Asn Ser Pro Leu Gly Glu Arg Leu Glu Val Asp Thr Glu Leu 1 5 10 15 Ser Pro Arg Leu Gln Glu Ile Ser Leu Asn Ser 20 25 32 amino acids amino acid single linear peptide not provided 2 Asp Pro Thr Arg Arg Pro Tyr Lys Leu Pro Asp Leu Cys Thr Glu Leu 1 5 10 15 Asn Thr Ser Leu Gln Asp Ile Glu Ile Thr Cys Val Tyr Cys Lys Thr 20 25 30 14 amino acids amino acid single linear peptide not provided 3 Met Ala Arg Phe Glu Asp Pro Thr Arg Arg Pro Tyr Lys Leu 1 5 10 32 amino acids amino acid single linear peptide not provided 4 Ala Ala Cys His Lys Cys Ile Asp Phe Tyr Ser Arg Ile Arg Glu Leu 1 5 10 15 Arg His Tyr Ser Asp Ser Val Tyr Gly Asp Thr Leu Glu Lys Leu Thr 20 25 30 48 amino acids amino acid single linear peptide not provided 5 Val Leu His Leu Glu Pro Gln Asn Glu Ile Pro Val Asp Leu Leu Cys 1 5 10 15 His Glu Gln Leu Ser Asp Ser Glu Glu Glu Asn Asp Glu Ile Asp Gly 20 25 30 Val Asn His Gln His Leu Pro Ala Arg Arg Ala Glu Pro Gln Arg His 35 40 45 13 amino acids amino acid single linear peptide not provided 6 Ile Asp Gly Val Asn His Gln His Leu Pro Ala Arg Arg 1 5 10 20 base pairs nucleic acid single linear DNA (genomic) not provided 7 TCCAGACGTT AGTAAATGAA 20 

We claim:
 1. A vaccine comprising at least one peptide chosen from I) DPTRRPYKLPDLCTELNTSLQDIEITCVYCKT (SEQ ID NO: 2), II) MARFEDPTRRPYKL (SEQ ID NO: 3), and III) AACHKCIDFYSRIRELRHYSDSVYGDTLEKLT (SEQ ID NO: 4).
 2. A vaccine comprising at least one chosen from I) VLHLEPQNEIPVDLLCHEQLSDSEEENDEIDVGNHQHLPARRAEPQRH (SEQ ID NO: 5), and II) IDGVNHQHLPARR (SEQ ID NO: 6).
 3. A diagnostic composition for identifying viral proteins in patients' sera, comprising polyclonal or monoclonal antibodies with specificity for the seroreactive epitope on a peptide, wherein said peptide comprises at least one seroreactive epitope selected from the group consisting of I) DPTRRPYKLPDLCTELNTSLQDIEITCVYCKT (SEQ ID NO: 2), II) MARFEDPTRRPYKL (SEQ ID NO: 3), and III) AACHKCIDFYSRIRELRHYSDSVYGDTLEKLT (SEQ ID NO: 4).
 4. A diagnostic composition for identifying viral proteins in patients' sera, comprising polyclonal or monoclonal antibodies with specificity for the seroreactive epitope on a peptide, wherein said peptide comprises at least one seroreactive epitope selected from the group consisting of I) VLHLEPQNEIPVDLLCHEQLSDSEEENDEIDVGNHQHLPARRAEPQRH (SEQ ID NO: 5), and II) IDGVNHQHLPARR (SEQ ID NO: 6). 